Hi There!

I have a problem with a legacy Tomcat application running on a windows environment where the Old Gen heap space is gradually hitting close to 100%, where it becomes immune to immediate garbage collection and causes the appl= ication to become unusable.

The environment details are as follow;

Platform – Windows Server 2003 En= terprise Edition SP1 (8GB RAM)

Apache/Tomcat Version – 5.5.15

JVM Version – 1.5.07 (Server JVM)

Database – SQL Server 2005 (separate server)

Database Connector – jTDS 1.2 JDBC driver

Tomcat is installed as a service so all JVM parameters are controlled via the Tomcatw.exe. They are as follows

-Dcatalina.home=3DF:\tomcat5

-Dcatalina.base=3DF:\tomcat5

-Djava.endorsed.dirs=3DF:\tomcat5\common\endorsed<= /font>

-Djava.io.tmpdir=3DF:\tomcat5\temp

-Djava.util.logging.manager=3Dorg.apache.juli.ClassLoaderLogManager<= o:p>

-Djava.util.logging.config.file=3DF:\tomcat5\conf\logging.properties=

-Duser.language=3Den

-Duser.country=3DGB

-Xms1500m

-Xmx1500m

-XX:+UseParallelGC

-XX:ParallelGCThreads=3D2

-XX:+UseParallelOldGC

-XX:+UseAdaptiveSizePolicy

-XX:NewSize=3D400m

-XX:MaxNewSize=3D400m

-XX:PermSize=3D128m

-XX:MaxPermSize=3D128m

-Dcom.sun.management.jmxremote.ssl=3Dfalse<= /p>

-Dcom.sun.management.jmxremote.authenticate=3Dfalse

-Dcom.sun.management.jmxremote.port=3D1234<= /p>

-Dcom.sun.management.jmxremote.password.file=3DC:\Program Files\Java\jre1.5.0_06\jre\lib\management\jmxremote.password

All of these parameters are entered in the Java Options space in the Tomcat Management tool. Note below that the active values for -Xms and -Xmx appear to be the ones stipulated in Initial Memory Pool and Maximum Memory Pool.

One thing I have been trying is to increase the JVM memory pool to take advanta= ge of the memory in this server (nothing else runs on the box). The high= est I appear to be able to set it to is about 1350 MB. Reading through so= me doco I see references to this saying to set it to multiples of 1024. I attempted to set to 2048 MB as the server has more than enough memory to cope. Tomcat refuses to take anything more than 1350 MB!

As you can see by my judicious use of GC parameters (!) I have also tried tuni= ng the garbage collector to aggressively clean the Old Gen heap. This settled things down for a while but if the JVM is left unattended for a few hours the Old Gen builds up and sometimes ‘freezes’ as explained before. Sometimes a manual GC with JConsole helps but this is hardly ideal! GC sure is a barrel-o-fun!

Can anybody offer some suggestions to resolve this?

Cheers,

Darren Kukulka

IT Infrastructure Consultant

Conntrol

Connaught PLC